Reenforced bridge span



R. MODJESKI- REENFORCED BRIDGE SPAN. APPLICATION mm SEPT.Y26', 192 1.

, Patented MayBO, 1922.

4 suns-sugar 2.

INVENTOR.

MAMA/2?! ATTORNEY,

R. MODJESKI- v REENFPRCED BRIDGE SPAN. APPLlCATlON man SEPT-2.6.1921.

1,417,93 Patented May 30, 1922.

4 snmsesuzsr 4.

INVEN TOR.

ATTORNEY UNITED STATES RALIEH MODJ'ESKI, 0F PHILADELPHIA, PENNSYLVANIA,

REENFOBCED BRIDGE SPAN;

Application filed September 26, 1921.

To all 10710772 it may concern:

Be it known that I, RALPH hlODJESKI, a citizen of the United States, anda resident of Philadelphia, in the county of Philadelphia and tit-ate ofPennsylvania, have invented a Reenforced Bridge Span, of which thefollowing is a specification.

This invention relates to bridges and relates particularly to railwaybridges of the type known as through bridges.

It is a matter of common knowledge that within a period of comparativelya few years the character of railroad rolling stock has changed verymaterially, both locomotives and cars being much larger and heavier andthe cars being loaded much more heavily than formerly, thuscorrespondingly increasing the live load to which bridges are subjecteddue to the weight of trains passing over them.

As a result of this change, it has been found necessary in many cases toreinforce and strengthen old railroad bridges, or where this wasimpossible or impractical for any reason, to replace the old'structurewith a new one of sul'lioient strength to meetpresent day requirementswhile at the same time maintaining trailic on the oldstruo ture.

The objectof the present invention is to provide a construction for thusreinforcing and strengthening the spans of through bridges, which willinvolve practically no change in the original bridge structure and iwill permit the original structure to remain practically undisturbedduring the strengthenin g process.

I effect the ob'ect of the invention by means ofwhat may be designated.a supple mentary span erected between the trusses of the original span,said supplementary span being erected at asutliciently higher level thanthe original span so that it will be entirely above the floor of saidoriginal span, which will thus present no obstruction to the erection ofsaid supplementary span and neednot be disturbed, web members of thetrusses of said supplementary spa-n be ing extended downwardly-forminghanger mem'bers-and being riveted to the floor beams of the originalspan, whereby a pro portionate part of the live load on the span and.under certain conditions, of the dead load, will be transferred to andborne by said supplementary span.

Also, in order that deflection and other Specification of LettersPatent.

Serial No. 503,187.

case they are cross braced, the cross braces of the supplementary span,so far aspraCticable, will preferably be bullt around correspondingbracing members of the original span so as to enclose them, thusavoiding interference with the bracing of the original span and leavingit practically intact. If not cross braced, the trusses of thesupplementary span may and preferably will be supported against lateralstresses, as wind pressure, by connecting them to the trusses of theoriginal span on tlieisame sides of the Convenient means for thispurpose lgnfidge. consists of angle brackets secured to theupright trussmembers of the supplementary span and to the top chords of the trussesofthe orlginal span. It considered deslrable, my inventlon contemplatesthe use both of cross bracing and connecting brackets.

If it is desired that the supplementary span, in addition to carryinglts proportionate Patented May 30, 1922;

share of the live load, shall also carry part of the dead load'represented by the weight of the originalspan, this may be efi'ectedbystressing the supplementary span so as to defleet it, or by relievingthe stresses in the original span so as to increase its camber, betoreconnecting the hanger web members of said supplementary span to thefloor beams of the original spa-11, or, preferably, by both stressingthe supplementary span and relieving the stresses in the original span.Simple means for this purpose may consist in connecting original andsupplementary spans byrods, comprising sections connected byturn-buckles, which will thus form in effect lifting jacks. Myinvention, however, contemplates the use for this pur pose of any formof lifting means suchas' will readily suggest themselves to bridgeengineers and others skilled inthe erection of this type of structure.

A reenforced bridge structure of my invention also comprises the variousother features, combinations of features and details of constructionhereinafter described and claimed.

In the accompanying drawings, in which my invention is fullyillustrated,

Figure l is a side view of a through bridge span reinforced inaccordance with my invention.

V Figure 2 is a sectional elevation thereof comprising right and lefthand half sections taken on the lines 2-2 and 2-2, respectively,of Flg.1.

Figure 3 is a fragmentary side view, on

I tional elevations taken on the lines (B -6 and 7.7, respectively, ofFig. 2, and

: Figures 8, 9 and 10 are fragmentary detail views taken, substantially,from the positions 8-8, 9-9 and l0-10, respectively,

of Fig. 2.

Referring now to the drawings, A designates, as a whole, the original orold span of a bridge reenforced in accordance with my invention, and Bthe supplementary or new span, said spans respectively.comprising-trusses A A and B B Excepting in minor and unimportantdetails, said spans A, B, and the trusses forming parts thereof,respectively, are geometrically duplicates of each other. s

As regards their usual features and excepting as to features hereinafterparticu larly pointed out and described, the spans A and B, shown, aremerely typical-exemplifying generally the application of my inventionand improvements for reinforcing and strengthening all types of thethrough bridges, where trusses of original spans are spaced far enoughapart to its use.

As'regards their usual features, also, the construction of said spansand trusses will be readily undertood by bridge engineers and otherfamiliar with bridgedesign from an examination of the drawings, withoutdescription thereof in detail.

What may be considered the basic feature of my invention, consists inerecting thesupplementary span B at a sufficiently .higherlevel than theoriginal spanthat said supplementary span will be entirelyabove thefloor ofthe original span and may thus be erected without tearing outthe fioor and without disturbing it, excepting in very slight respects.

In carrying out my invention, as it relates to this broad feature, Iprovide new footing for supporting the supplementary span erected on theoriginal-piers or foundation of the bridge, indicated at C, said newfootings being positioned between and closely adjacent to the shoes oforiginal span, designated D. For purposes of coni venient reference,said new footings will be designated as a whole D.

As shown, said footings D comprise blocks 1, consisting preferably ofsteel. castings, which rest directly upon the tops of the piers G,girders 2, the ends of which rest upon said blocks 1 and are connectedby diaphragms 3, and shoes 4 supported by said girders and diaphragms,resting di rectly upon cover plates 5 secured to the tops thereof.

In the preferable construction shown, also, all of the footings D, D forboth spans at the same ends thereof, are rigidly con nected or tiedtogether by connecting the ends of the girders 2 to plates 6 insertedbeneath the ends of the trusses A, A and resting upon the top sides ofthe shoes D for the original span, as shown at 7, Fig. 4.

In the drawings, I have shown my invention and improvements, as theyrelate to the footings of supplementary spans, asapplied for supportingthe contiguous ends of adjacent spans of bridges comprising a pluralityof spans. The adaptation thereof for reinforcing bridges consistingofonly one span, will, however, involve no departure in principle from theapplication shown, and will be obvious to persons familiar with bridgeconstruction and design from the disclosure of the drawings.

In order that the supplementary span B shall carry a predeterminedproportionate share of the loads to which the bridge is subjected inuse, web members of the trusses B, B of the supplementary span 13 areextended downwards and are riveted or rigidly attached to the floorbeams 8 of the bridge.

If the supplementary span B is designed to strengthen the bridge underlive loads only, the members of said supplementary trusses will beconnected to the floor beams of the bridge, while under normaldeflection only, due to its own weight.

If, on the other hand, said supplementary span is designed to carry aportion of the dead load represented by the weight of the original spanA, this ma be edected by stressing the trusses B, B thereof to increasetheir deflection to correspond to. a desired dead loading thereof beforethe web members of said trusses are-connected to the floor beams 8 ofthe bridge-or, what" nan/ps6 would amount to, the same thing, by relieving the stresses in the trusses of the original span A to increase theircamber, or by bothstressing the trusses of the supplementary span andrelieving the stresses in the trusses of the original span to increasethe deflection and camber thereof, respectively. Means for, this purposewill readily suggest themselves to engineers and erectors and, as theyform. no part out the invention per se, it is unnecessary to either showor describe the same.

As shown, the trusses A", A and. B, B are connected by sway bracing. ofthe character commonly used on relatively long, high spans. Said swaybracing will be readily understood by ln'idge engineers from anexanimation of the drawings and 1t need not,

therefore, be described in detail, excepting);

as regards certain features peculiar to bridges reentorced in accordancewith my invention.

One such feature is presented by certain of the web members of the.trusses ol the supplementary span which extend down and connect to thefloor beams of the bridge and which comprise spaced shapes connectedbybatten plates or lacing, the characteristic feature of which is thatsaid shapes are dis posed on opposite sides of the floor beams to whichthey are to be connected, respectively, as shown particularly in Fig. 7.

Another such feature is shown in Fig. 6 of the drawings andhasparticular reference to sway braces ot the original span which intcrsectweb members of the supplementary span; consisting of rigidly connectedspaced structural shapes. One characteristic feature illustrated in saidI 6 is that the structural shapes forming said members are positioned onopposite sides or said bracing and are spaced a suiiicient distanceapart to permit said bracingmembers to pass between them.

Still another feature, also shown in Fig. (5, relates to sway bracingot' the original and supplementary spans consisting of structural shapessecured together in spaced relation by lattices, batten plates or thelike, and which extend parallel with and normally would be positionedone above the other a distance equal to the elevation of the supplcn'ientary span above the original span. As regards this feature, Icontemplate lowering' the bracing of the supplementary span so that itsaxis will coincide substantially with the axis of corresponding bracingof the original span, and building the bracing ot the supplementary spanaround that of the original span so as to enclose said original bracinp;and conceal the same. thus obviating interference of the new bracingwith the old and rendering the sway bracingof the reentorced structureless intricate and more sightly in appearance.

In accordance with my invention, also, the trusses of the orlgi-nal andsupplementary spans on the same side of the bridge are rigidly connectedtogether, thus imparting stiffness and rigidity to the reenforcedstructure to resist lateral stresses. Simple means for this purposeconsists of angle brackets 9, which either connect. the top chords ofthe trusses of said original and supplementary spa-us directly, as shownin Figs 2 and 9, or the top chord of the original span with web membersOil the trusses oi the supplementary span adjacent to the top chordsthereof, as shown in. Figs. 2 and 8.

Also, if the sway bracing of the original span is su'fliciently strongor can be reeniorcedto make it sufliciently strong to support thetrusses of both spans of the reenforred bridge against; lateralstresses, invention contemplates dispensing entirely with sway bracingfor the supplementary trusses and supporting the same against lat eralstresses by connecting the trusses thereof to the trusses of theoriginal span by.

brackets, in the manner described. Or, if

desired. m invention contemplates theuse of both. forms of sway bracingfor said supplementary span.

1. In areeniiorced bridge structure the combination of an' originalspancomprising;

trusses, end supports therefor, and. a floor comprising transverse floorbeams, asupplement a-ry span comprising trusses, and end supportstherefor positioned suiiicientlv higher than the end supportsitor. theoriginal span that said supplementary span will clear the floor of thebridge, the trusses 0t said supplementary span comprising web memberswhich are extended down and are connected to the floor beams of thebridge, substantially as described.

2. A reentorced bridge structure as specified in claim 1, in which saidtrusses are substantially geometrical duplicates of each other,substantially as described.

3. A reenforced bridge structure as specified in claim 1, in which thefloor of the bridge comprises girders the ends of which are built intoand rigidly connect the end supports for the trusses of thesupplementary span at opposite sides thereof, sub stantially asdescribed.

4. A reenforced bridge structure as specified in claim 1, in which theend supports for corresponding ends of the trusses of the original andsupplementary spans are rigidly connected, substantially as described.

5. A reenforced bridge structure as specified in claim 3, in which theend supports for corresponding ends of the trusses of the original andsupplementary spans are rigidly connected, substantially as described.

6. A reeniorced bridge structure as specitied in claim 3, in which theend supports for the trusses of thesupplementary span comprise baseblocks on which the floor girders incorporated into the end supports ofI said supplementary span rest, substantially as described.

7. A reenforced bridge structure as specifled in claim 2, in which thetrusses of the original span are connected by sway bracing, and thetrusses of the original and supplementary spans on the same side of thebridge are rigidly connected to each other adjacent to their top chords,substantially as described.

8. A reenforced bridge structure as specitied in claim 2, in which thetrusses oi the original span are rigidly connected by sway bracing, theweb members of the trusses of the supplementary span intersected therebycomprising spaced members so disposed that said intersecting swaybracing will extend between the same, substantially as described. 9. Areentorced bridge structure as Specitied in claim 8, in which trusses ofthe original and supplementary spans on the same side of the bridge arerigidly connected adjacent to their top chords, substantially asdescribed. v

10. A reenforced bridge structure as specified in claim 1, in which thetrusses of the original and supplementary spans are rigidly connected bysway bracing, comprising bracing for, said spans, respectively the axesof which are substantially coincident, and the bracingfor saidsupplementary span is built around and incloses the bracing for saidoriginal span, substantially as described.

11.. A reeni'orced bridge structure as specified in claim 10, in whichthe sway bracing for the original span intersects web members of thetrusses of said supplementary span and the web members or saidsupplementary span intersected v thereby comprise spaced members sodisposed that the intersecting sway bracing will extend between thesame, substantially as described.

12. A reentorced bridge structure as specified in claim 1, in which thetrusses of the supplementary span are deflected before the web membersthereof are connected to the floor beams of the original span, to transfer a portion of the dead load represented by the weight of the originalspan to said supplementary span, substantially as described.

13. A reenl'orced bridge structure as specificd in claim 1, in which thestresses in the original spa-i1 are relieved to increase its canrberbefore the web members 01 the supplementary span are connected to thefloor beams of said original span, to transfer a portion of the deadload represented by the weight of the original span to saidsupplementary span, substantially as described.

14. A reenforced bridge structure as speci fied in claim 12, in Whichthe stresses in the original span due to its weight are relieved,substantially as described.

15. A reentorced bridge structure as specified in claim 1, in which thetrusses of the supplementary span are erected inside of the trusses ofthe original span, substantially as described.

In testimony that I claim the foregoing as my invention, I have hereuntoaiiixed my signature this fifteenth day of September, 1921.

7 RALPH MODJESKI.

